Automatic alternating-current cut-out device for polyphase circuits



March 8 1927.

M. NJMIKULIC AUTOMATIC ALTERNATING CURRENT CUT-OUT DEVICE FOR POLYPHASE CIRCUITS Filed June 5. 1922 Patented Mar. 8, 1927.

UNITED STATES PATENT OFFKIE.

MILOS N. MIKULIC, OF KANSAS CITY, MISSOURI.

AUTOMATIC ALTERNATING-CURRENT CU'IOUT DEVICE FOR POLYPHASE CIRCUITS.

Application filed June 3,

One of the principal objects of the invention is to provide an automatic cut-out switch which will be operative to protect the motor or other electrical apparatus from being operated on less than the normal number of phases in the circuit, so that the motor or other apparatus will not be burned out or otherwise injured due to continued operation after the circuit has been broken through one of its phases.

In industries using the alternating form of electric current, it is well known that the current on one or more phases may become interrupted, due to loose contacts, short circuiting, opening of primary winding of motor, low voltage, blowing of fuses, etc.

Accordingly I have devised an improved safety device which consists in providing each of the phases of the circuit with an elect-ro-inagnetically operated armature the release of which, in response to an interruption of the circuit through that phase, will cause the armature to automatically engage and actuate a switch for breaking the circuit through all its phases, and thus render the motor or other electrical apparatus included in the circuit inoperative until any repairs that may be neces ary have been attended to.

With these general objects in view, the invention will now be described by reference to the accompanying drawing illustrating one practical form of embodiment of the proposed improvements. after which the novel features therein will be particularly set forth and claimed.

In the drawing Figure 1 is an end view, with a portion of he casing broken away, illustrating an automatic safety cut-out device embodying the present invention;

Figure 2 is a front view of the same, also illustrating the casing broken away to disclose the interior operating parts; and

Figure 3 is a perspective view of the protective switch and the contact points, this view illustrating diagrammatically the circuit connections, and the operative relation of the switch cutout armature members.

Referring now to the drawing in detail, this illustrates the improved device as comprising a framework 4- adapted to be partially enclosed by a housing or casing 5 in which a suitable supply of oil may be maintained to prevent any undue sparking which 1922. Serial No. 565,703.

might otherwise be produced by the opening of the cut-out switch. Each of the branches or phases of the circuit, represented by the conductors 6 is connected with a knife contact 7, these contacts being adapted to be engaged by one of the elements 8 of a three pole switch member pivotally connected at 9 to the framework of the device. Each of the phases 6of the circuit is also provided with the usual fuse element 10, and is further provided with a suitable electromagnet 11, each electromagnet having associated therewith an armature element- 12 of approximately bell crank shape, these armatures 12 being pivotally mounted at their middle portions upon a rod or shaft 14. The lower portions of the armatures 12 are connected to springs 15, the rear ends of which are attached to screws 16 carried by the frame l of the device. This arrange- -ment is such that on release of the armatures 12 from the electromagneti; 11 the armatures will swing under the combined action of gravity and the tension of the springs 15, to engage the lower ends of the armatures with one of the transverse portions 18 of the switch member, as represented in Figure 3 and by the broken lines in Figure 1, for the purpose of disengaging the switch element 8 from tile contacts 7 and thus simultaneously breaking the circuit through all the phases 6 of the same.

For initially closing the circuit through all the phases thereof, 1 provide a lifting device comprising a bail member 20 which is pivoted upon the rod or shaft 1 1 and pro vided with a handle portion 21. ihe raising of this bail 20 by means of a handle 21 causes it to engage the upper portions of the armatures 12, and force the same backward into contact with the co responding electromagnets 11. The intermediate portion of the bail 20 carries a suitable bracket ele ment 22 to which is pivotally connected the upper ends of a pair of links 23 having their lower ends secured to a bar or plate 24 the opposite ends of which are slidingly mounted in guideways 25 provided in the framework 4 of the device. This bar 24; carries an inwardly projecting strip 26 adapted, on lifting of the bar 24 by means of the handle 21 and bail 20, to engage the extreme end portion of the switch element and thereby lift the switch elements 8 into engagement with the knife contacts 7 simultaneously with the raising of the armatures 12 into engagement with the electromagnets 11;

An independent switch operating device is also provided in the form of a vertical rod 28 slidingly carried in the framework of the device and having its lower end connected, as indicated at 29 (Figure 2) to the cut-out switch, the upper end of said rod 28 having a knob 30. This rod 28 and knob portion 30 thus afford a manually operable connection for throwing the switch into either open or closed position independently of the operation of the other mechanism above described.

In the usual construction of three-phase motors, the blowing of a fuse or interruption of the circuit in any one phase of the circuit will simply allow the motor to continue running on the remaining phases, with consequent overheating or eventual burning out of the motor, unless the faulty condition is corrected promptly. With the present improved device as above described installed in the circuit, in the event of the current through one of the phases being interrupted, the corresponding electromagnet 11 in that phase of the circuit will at once release its armature 12, and the latter will at once actuate the switch and disengage the switch elements 8 from all the Contact points 7, as illustrated by the dotted lines in Figure 1, thus breaking the circuit through all phases of the same. This operation takes place instantly, and without the presence of the attendant to note the faulty condition in any of the phases of the circuit, so that his attention is merely required to replace the blown out fuse or make any other repair necessary in that phase of the circuit through which the current was first interrupted. After the proper attention has been given, the only action necessary to resume the currentoperation is to elevate the bai 20 by practical, efficient as well as very simple and inexpensive construction for embodying the proposed improvements, this construction comprising comparatively few parts simply arranged and not likely to get out of order. The device is also of very compact construction, so that the same may be operated on motors of practically all sizes.

While I have illustrated what I now regard as the preferred form of construction for embodying the invention, I desire to be understood as reserving the right to make such changes or modifications as may fairly fall within the scope of the appended claims.

What I claim is:

1. An automatic cut-out device for polyphase circuits comprising a normally open switch operative to close the circuit simultaneously through all its phases, an electromagnetic device included in each phase of the circuit, an independent armature asso- 'ciated with each of said electromagnetic devices, said armatures being each movable from a position some distance away from said switch into engagement with the latter, whereby each armature is operative automatically on release from its corresponding electromagnetic device to strike the switch and actuate the same by impact into open position, and manually operable means for simultaneously reengaging said armatures with said electromagnetic devices and simultaneously actuating said switch into closed positlon.

2. An automatic cut-out devicefor polyphase circuits comprising a normally open switch operative to close the circuit simultaneously through all its phases, an electromagnetic device included in each phase of the circuit, an independent armature associated with each of said electromagnetic devices, said armatures being each movable from a position some distance away from said switch into engagement with the latter, whereby each armature is operative automatically on release from its corresponding electron'iagnetic device to strike the switch and actuate the same by impact into open position, manually operable means for simultaneously reengaging said armatures with said electromagnetic devices and simultaneously actuating said switch into closed position, and an independent manually operable device for actuating said switchinto either open or closed position.

Signed by me this 22d day of May, 1922. MILOS N. MIKULIC. 

